‘Love Hormone’ Oxytocin Can Also Breed Fear, Anxiety

Oxytocin is the name of a natural substance, classified as a hormone, which forms in the brain and circulates throughout the bloodstream. During childbirth, doctors can use oxytocin injections to induce labor, quicken labor or decrease the risk for bleeding immediately following labor. Scientific evidence indicates that this hormone also plays a vital role in the human ability to experience well-being and feel love toward others, and researchers are currently exploring oxytocin’s usefulness as a treatment for medically serious anxiety. However, according to the results of a new study published in July 2013 in the journal Nature Neuroscience, use of oxytocin can also potentially increase a person’s level of anxiety and contribute to a worsening of mental health.

Beneficial Effects of Oxytocin

Oxytocin exerts its effects on human well-being by interacting with certain cells in the central nervous system (brain and spinal cord). Numerous studies point to the hormone’s importance in maintaining or increasing mental equilibrium in a range of circumstances. For instance, a study published in 2008 in the journal Psychological Science indicates that pregnant women rely on the oxytocin in their systems to form care bonds with their developing children. The authors of this study found that pregnant women with relatively high oxytocin levels form firmer mother-child bonds than women with relatively low levels of the hormone. The authors of another study, published in 2005 in the Proceedings of the National Academy of Sciences, found that adopted children (whose adoptive mothers did not experience the pregnancy-related effects of oxytocin) sometimes have difficulty forming solid bonds with their parents and with other people. In a study published in 2012 in the journal Psychoneuroendocrinology, a team of Israeli researchers examined the role of oxytocin in supporting the pair bonding that occurs when people start new romantic relationships. After reviewing their findings, these researchers concluded that oxytocin levels in new lovers far exceed the levels found in pregnant women, and help explain the strong bonds that frequently form during a relationship’s early stages. Generally speaking, the amount of oxytocin present in individuals during the initial stages of a relationship also helps predict whether those relationships will continue for extended periods of time.

Potentially Harmful Effects

In the study published in Nature Neuroscience, researchers from Northwestern Medicine used laboratory testing of mice to examine oxytocin’s influence on the brain’s ability to adapt to stressful situations and store emotions in the form of positive memories. Based on the slew of previous studies highlighting the beneficial effects of the hormone, these researchers expected to find that oxytocin plays a supportive role in the memory formation process. However, the opposite outcome occurred. When exposed to situations designed to trigger a strong stress reaction, mice with high levels of oxytocin in their bodies had a much greater tendency than mice with low oxytocin levels to store their stress-related experiences as fear-inducing bad memories. In a second stage of testing, the Northwestern Medicine researchers exposed mice to stress-inducing situations and followed up this exposure with a brief, mild electrical shock. When they were later reintroduced into the setting where they received the electrical shock, mice with high amounts of oxytocin in their systems showed clear signs of anxiety that indicated an anticipatory fear of receiving another shock. On the other hand, mice with low levels of oxytocin in their systems displayed a much lower level of anticipatory fear and anxiety.

Significance

The authors of the study in Nature Neuroscience believe that they are the first researchers to clearly demonstrate that the presence of oxytocin can have a harmful effect on fear and anxiety levels, as well as a positive effect. Their findings echo and clarify the work of several previous human studies, which also point toward oxytocin’s potential to increase anxiety levels. The study’s authors believe that social setting plays a large part in determining whether oxytocin will contribute to an improved sense of love and well-being or contribute to an increase in anxiety and fear. In situations with a loving undercurrent, the hormone apparently supports well-being, while it apparently supports anxious and fearful reactions in highly stressful situations. Since several research groups are developing oxytocin-based medications as anti-anxiety treatments, the context of those treatments may go a long way toward determining whether oxytocin helps or hurts the individual.